CO 00 t


Blue Violet

Electron jumps from 4th tcf 1 st excited states violet light (4341 A) -emitted y~


Lines are named in order, using letters of Greek alphabet

Color of line

Figure 3.4. Origin of the unique set of bright red, blue, and violet emission lines of hydrogen. (Ground state not shown.)

Figure 3.5. Origin of the dark absorption lines corresponding to the bright red, blue, and violet emission lines of hydrogen.

If the right energy is supplied, an electron will jump to a higher energy level. Then the atom is in an unstable excited state. When the electron falls back down, the atom radiates that energy in the form of a pellet of light called a photon.

If an atom absorbs enough energy, one or more of its electrons can be removed completely. The atom, which is left with an electric charge (positive), is then called an ion.

Bright-colored emission lines are produced when electrons jump from higher energy levels back down to lower energy levels. The wavelength of the light emitted is inversely proportional to the energy difference between the energy levels. Since each kind of neutral or ionized atom has its own unique set of energy levels, each chemical element has its own unique set of bright-colored emission lines (Figure 3.4).

Corresponding unique dark absorption lines are produced when an atom of a chemical element absorbs light and the electrons jump out to higher energy levels (Figure 3.5).

Thus, an emission spectrum or a corresponding absorption spectrum gives positive identification of the chemical element that produced it.

Why do atoms emit light of different colors (specific wavelengths)?_

Answer: Each color (wavelength) corresponds to an electron jumping down from a particular higher energy level to a particular lower energy level.

Figure 3.6. The starlight we observe comes from a star's photosphere and passes through its outer atmosphere before shining into space.

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